What Is an Octant?

The octant error refers to the azimuth error caused by the limited spacing between antenna elements in a system using a diversity antenna array to provide azimuth information. The error value changes in a sinusoidal manner over a range of 360 degrees, with four positive and four negative maximums.

The octant error is provided by using a diversity antenna array.

The role of diversity reception in base stations was first reported in 1965, and it was pointed out that setting two antennas at a distance of 10 wavelengths in the horizontal plane can reduce the effects of fading. Although diversity reception requires two or more ports, it significantly reduces the effects of fading. As a result, mobile station transmission power is reduced and transmission quality is improved, which is very beneficial to the entire system. In 1982, the United States first used base station diversity reception technology for commercial purposes; Japan's NTT large-capacity system also adopted diversity reception technology in 1985.

In the base station diversity antenna system, when the antennas are horizontally spaced, the received signal strengths of the two antennas are similar, so the larger the interval between the antennas, the smaller the probability of the two received signals fading simultaneously, so the better the diversity performance, Reduced effects of fading. When the antennas are vertically spaced, the two received signal strengths are not equal, so that no good diversity effect can be obtained regardless of the antenna spacing. Therefore, in practical commercial systems, the base station diversity antenna usually uses horizontal space diversity reception, and rarely uses vertical space diversity reception.

In the horizontal space diversity base station antenna system, it is generally required that the installation interval between the antennas of the primary and secondary diversity base stations is sufficiently large, so that the mutual interference between the antennas can be reduced, and the diversity performance of the antennas can be improved. In the project, the distance between the two base station antennas is generally 5 to 10 wavelengths. However, due to the increase in the number of antennas on the base station, the installation space of the antennas becomes very limited. Therefore, there is usually a mutual influence between the base station antennas, which causes distortion of the antenna pattern. Therefore, it is necessary to analyze the directional characteristics of the diversity antenna of the base station. ^[2]

The angular difference between the measured bearing and the corresponding true bearing.

The azimuth is the direction from a point on the ground to a point on the sky or another point on the ground. This representation is also called azimuth, which is one of the methods to measure the angular difference between objects on a plane. It is the horizontal angle from the north direction line of a point in a clockwise direction to the target direction line.